Machining tool for chip removal

ABSTRACT

The invention concerns a machining tool for chip removal, in particular a milling cutter, comprising a support ( 10 ) wherein is provided a housing ( 12 ) for a cutting element ( 14 ) equipped with a machining part ( 16 ) and a fixing part ( 18 ). The fixing part ( 18 ) includes a base part ( 20 ) which is placed in the housing ( 12 ) in receiving position ( 22 ) and which, when it its rotated into interlocking position ( 26 ) meshes beneath at least one retaining flange ( 26 ) of the housing ( 12 ), being thereby capable of being used with the cutting element ( 14 ) for chip removal matching. It is therefore possible to fix said cutting element without additional retaining means, such as a fixing screw or the like, its simple insertion into the housing and its interlocking position by rotation providing a reliable fixing method. Conversely, said cutting element can be released from its interlocked position and extracted from the housing hardly with very little force.

The invention relates to a machining tool for chip removal, a millingtool in particular, having a holder wherein there is provided a toolcarrier for a cutting element which has a machining part and a fasteningpart.

Tools such as these are readily obtainable on the market in a pluralityof embodiments and in the known designs there are various possibilitiesfor interchangeably fastening the cutting element which consistspreferably of carbide material which is subject to wear duringmachining, on a holder. Thus German Patent DE 34 48 086 C2 disclosesputting an annular cutting element which is provided radially on itsoutside circumference with a machining edge by way of three crown-shapedribs, which are diametrically opposite one another and which are locatedon its bottom, in correspondingly configured fastening grooves whichwiden conically to the outside on the end side of the holder in order tofix the cutting element in this way on the holder by way of a conicalfastening screw, which on the end side extends through the center recessof the cutting element. The approach here allows moment-free support ofthe cutting element on the holder in machining with the machining edge.The initiation of harmful vibrations which may adversely affectmachining is also largely precluded in this way. The known tool inquestion is generally used for machining of internal recesses. Thefastening process by means of a fastening screw is disadvantageous sinceit must be loosened and retightened each time for the process ofreplacing the cutting element. Consequently, this replacement processrequires some time for the fastening process in the scope indicated.

DE 195 22 452 C1 discloses a milling tool, especially a circular miller,with a shaft part which may turn along an axis of rotation, and a headpart on which there is at least one machining edge on thecircumferential side, the shaft and head part being connected to oneanother torsion-proof by fitting into one another by way of engagementmeans of one part which precisely adjusted engage the assigned recessesof the other part with contact along driver surfaces. The respectiveengagement means along its outer circumference has a centering surface,which undergoes transition in the direction of the axis of rotation ofthe tool into the driver surface, which together with the centeringsurface is encompassed by the respectively assigned recess and isbordered on the circumferential side by the shaft or head part. Theknown approach accordingly relates to a versatile milling tool, whichhas a very space-saving antirotation means, the respective machiningedge designed to be interchangeable, and with the known approachmachining may be carried out without failures in a definable diameterrange. To secure the head part on the shaft part, the head part isprovided with three internally threaded holes, the respective hole axishaving a slight offset relative to the corresponding internally threadedholes in the shaft part so that when the head part is secured with therespective machining edge by way of the corresponding engagement screws,the indicated offset is equalized and the indicated parts are fixed onone another by way of the respective centering surface of the engagementmeans with zero play for a machining process. This approach for thereplacement process of the head part with cutting elements is verytime-consuming and this approach is also complex with respect to thetechnical implementation.

PCT/WO 98/50187 discloses a metal-cutting tool in which a cuttingelement with a carbide material machining edge has a middle centeringrecess into which a mounting rod may be inserted in the fixed state byway of the head part located on the end side, the rod's fastening thecutting element with the center recess by way of conically arrangedcentering surfaces into the corresponding recesses on the free end ofthe assignable holder in a torsion-proof and axially secured manner.Here the pertinent fastening rod is pressed against a compressionspring, which is located in the holder with its other opposing end forthe fastening process of the cutting element and as soon as the fixedposition for the cutting element is reached, by way of a set screw,which extends through a widening of the holder at an oblique angle, thefastening rod is secured in the holder by the set screw being pressed bytightening against the groove of the fastening rod located on the outercircumferential side. As a result of the plurality of parts, this knownapproach is complex and consequently expensive to implement and severalhandling processes must be combined with one another for the fasteningprocess, such as actuating the set screw, adjusting the fastening rod,and pressing it against a compression spring located in the holderduring the installation process. In this respect, the process ofreplacing the cutting element with the machining edge is alsotime-consuming and requires an extensive installation effort.

On the basis of this state of the art, the object of the invention is tofurther improve the known tool such that the process of replacing thecutting element may proceed promptly and as intended and that theadvantages in the prior art are maintained, such as reliable delivery ofthe machining forces during metal cutting to the holder in order in sucha way to ensure high machining accuracy. This object is achieved by atool with the features of claim 1 in its entirety.

In that, as specified in the characterizing part of claim 1, thefastening part has a base part which may be inserted into the toolcarrier in a receiving position and which when turned into the lockingposition extends under at least one holding projection in the toolcarrier in order to be usable for metal cutting with the cutting elementin this way, the process of fastening the cutting element is possiblewithout any further fastening means such as a fastening screw or thelike and simply inserting the cutting element into the tool carrier andturning into its locking position reliably initiates a fastening processand in the reverse sequence the assumed locking position may also bereleased again with low actuating forces in order to remove the cuttingelement from the tool carrier. In the locking position the machiningforces, which occur during machining may also be reliably diverted intothe holder by way of the cutting element. The described tool isespecially suited in the configuration of a milling tool in which theholder is driven by way of a corresponding machine, such as a machinetool or drilling machine; but machining is also conceivable in which thetool is stationary and for the purposes of rotational machining theworkpiece is moved rotationally relative to the tool.

In one preferred embodiment of the tool as claimed in the invention, thetool carrier on the end side has a receiving channel which extendstransversely to the longitudinal axis of the holder and which may bepenetrated by at least one locking piece of the base part, the receivingchannel on the edge side being bordered by the respective holdingprojection under which the respective locking piece may extend in thelocking position. By extending under the holding projections in thedescribed manner, viewed in the axial direction, that is, in thelongitudinal direction of the holder, the cutting element is securelyheld in the tool carrier so that even in so-called rear machining, thatis, in the opposite feed direction, the cutting element remains securelyheld in the tool carrier.

In another, especially preferred embodiment of the tool as claimed inthe invention, the receiving channel on the end side leads into areceiving cone which widens toward the exterior and which may be broughtinto contact with a correspondingly configured centering cone of thefastening part in the locking position of the cutting element. If thebase part of the fastening part is turned into its locking position, thebase part pulls the centering cone of the fastening part of the cuttingelement onto the receiving cone to which the receiving channel leads,and on the outer circumferential side to the cutting element its securecontact with the holder in its longitudinal axis is thereby attained.

By preference, provision is furthermore made such that the centeringcone is adjoined by the machining part with at least one machining edge,preferably a triple-edged cutting plate, and that between the centeringcone and the machining edge there is a connecting part which is pulledin the longitudinal axis of the holder in the locking position of thecutting element against the outer circumferential edge of the receivingcone. But here contact with the outer circumferential edge does not takeplace, rather centering takes place by way of the conically adjoiningcontact surfaces; this allows accurate adjustment of the cutting elementon the end side of the holder.

In one especially preferred embodiment of the tool as claimed in theinvention, on the base part there are two locking pieces which arediametrically opposite one another, located on the free end of thefastening part, with the locking pieces being connected to the centeringcone which widens toward the exterior by way of a fastening shaft.During the fastening process, the centering cone is pulled against thecontact cone of the holder by way of the pertinent locking pieces on thebase part. Preferably this is additionally supported by the respectivelocking piece on its side adjacent to the centering cone being providedwith a bevel which slopes down in the direction of the free end of thefastening part. This bevel supports the described process of drawinginto the receiving cone of the holder.

In another preferred embodiment of the tool as claimed in the invention,within the tool carrier assigned to each locking piece there is a partof the thread with a lead which is oriented, beginning on the holdingprojection, in the direction of the inside wall of the tool carrier,which wall is closed on the end side. By way of the pertinent threadpart, the fastening process of the cutting element on the holder takesplace in the manner of a screwing-in motion and in this way an increasedtightening moment on the respective locking piece is produced.

If in one preferred embodiment of the tool as claimed in the invention,one of the two locking pieces is designed to be radially shorter thanthe other, the slotted receiving channel having one correspondinglylonger and one shorter receiving flank, it is ensured that the tool maybe moved into the receiving channel for a locking process only in onereceiving position. This may be of importance in particular when thecutting element is provided with only one machining edge and for massequalization the pertinent cutting element must then assume a definedfastening position relative to the holder.

The described tightening process is further supported in that the axiallength of the fastening shaft of the cutting element is at least greaterthan the length of the diametrically opposite holding projections on theholder, which length is measured in the longitudinal axis of the holder.

The tool as claimed in the invention is described in greater detailbelow using one embodiment illustrated in the drawings.

The figures are schematic and in part not to scale.

FIG. 1 shows in an oblique view the end side of the tool with thecutting element and holder,

FIG. 2 shows an end view of the holder without the cutting element;

FIG. 3 shows in a perspective view the rear of the cutting element;

FIG. 4 shows in a perspective front view the base part of the cuttingelement as shown in FIG. 3;

FIG. 5 shows, enlarged by a factor of 10, the end top view of the frontside of the holder as shown in FIG. 2;

FIG. 6 shows a section along line A-A as shown in FIG. 5.

The tool which is shown in the figures is used for metal cutting andrepresents in particular a milling tool with which, depending on themachining and cutting edge geometry, internal recesses in metalworkpieces or the like may be produced. The tool is provided with anoblong holder 10 for fastening the tool on a metal cutting machine, forexample in the form of a machine tool or the like. As FIG. 2 inparticular shows, the holder on its one free end has a tool carrier 12for holding the cutting element 14. The cutting element 14 has amachining part 16 and a fastening part 18 (cf. FIG. 3). The fasteningpart 18 has a base part 20 which may be inserted into the tool carrier12 in the holding position (cf. FIG. 5). If the base part 20 is turnedinto the locking position 24, that is, clockwise, the base part 20extends under two diametrically opposite holding projections 26 in thetool carrier 12 in order in this way to be usable for metal cutting.

As shown especially in FIGS. 2 and 5, the tool carrier 12 on the endside extending transversely to the longitudinal axis 28 of the holder 12has a receiving channel 30 in the manner of a transverse slot. Thisreceiving channel 30 may be penetrated by at least one locking piece 32of the base part 20, in the illustrated embodiment there being twodiametrically opposite locking pieces 32 on the base part 20 of thecutting element 14. The receiving channel 30 on the edge side isbordered by the respective holding projection 26 under which therespectively assigned locking piece 32 extends in the locking position24 of the cutting element 14. As FIGS. 2 and 6 show further, thereceiving channel 30 on the end side leads into the open by way of areceiving cone 34 which widens toward the exterior and which may bemoved into contact with the correspondingly configured centering cone 36of the fastening part 18 in the locking position 24 of the cuttingelement 14.

The centering cone 36 adjoins the machining part 16 with at least onemachining edge 38 preferably in the form of a conventional triple-edgedcutting plate 40. Here, between the centering cone 36 and the respectivemachining edge 38, there is an at least partially cylindrical connectingpart 42 which may be provided with a handle 44 for holding aconventional fastening tool, for example in the form of a hexagonalwrench or the like. Accordingly, the points which form the handle 44 areflattened relative to the other cylindrical parts of the connecting part42. But preferably it is provided that the cutting element 14 beinterchangeably inserted into the holder 10 by hand by taking hold atthe location of the triple-edged cutting plate 40, with the pertinentfastening and replacement process being detailed below.

The connecting part 42, which extends in the longitudinal axis 28 of theholder 10, is pulled in the fastening process of the cutting element 14and consequently in the direction of the locking position 24 of thecutting element 14 against the outer circumferential edge 46 of thereceiving cone 34. From the outer circumferential edge 46 of the holder10 to the outside it likewise widens conically until it undergoestransition into the cylindrical shaft part of the holder 10. Sincecontact takes place exclusively by way of the receiving cone 34 and theassigned centering cone 36, in the direction of the longitudinal axis 28of the holder there is a distance, even though short, of the connectingpart 42 relative to the outer circumferential edge 46 of the holder 10.

As furthermore is to be seen from FIGS. 3 and 4, the two diametricallyopposite locking pieces 32 are located on the free end of the fasteningpart 18 and are connected by way of a fastening shaft 48 to thecentering cone 36 which widens towards the exterior at a definable axialdistance. The respective locking piece 32 on its side adjacent to thecentering cone 36 is provided with a bevel 50 which slopes down in thedirection of the free end of the fastening part 18 to the outside at aflat angle. Furthermore, as shown especially in FIG. 4, the bevels 50may begin at different distances to the centering cone 36 on thefastening shaft 48, as they extend subsequently under the holdingprojections 26 in order thus to apply a tightening moment to therespective cone 34, 36. Preferably provision is made here for the factthat in the interior 52 of the tool carrier 12, assigned to each lockingpiece 32, at least one thread 54 is assigned with a lead beginning onthe holding projection 26, which lead is oriented in the direction ofthe inside wall 56 of the tool carrier 12, which wall is at leastpartially closed on the end side (cf. FIG. 6).

For the fastening process, the cutting element 14 with its two lockingpieces 32 is inserted into the tool carrier 12 such that the two lockingpieces 32 extend through the two flanks 58 of the receiving channel 30(cf. FIG. 5). The centering cone 36 of the cutting element 14 is thenpressed against the receiving cone 34 of the holder 10 by way of thetriple-edged cutting plate 40, and when contact is made, the cuttingelement 14 is turned clockwise by a definable swiveling path of thecutting element relative to the holder 10. As a result, the two lockingpieces 32 engage the respective thread 54 assigned to them and aresecured by extending in the locking position under the holdingprojections 26 which located transversely to the receiving channel 30border it to the exterior. For reliable delivery of force and momentduring machining, the cutting element 14 by way of its centering cone 36then adjoins the holder 10, and also by way of the two locking pieces32, in the area of their bevels 50. For the replacement process thedescribed fastening process must be carried out in the reverse sequenceand after removing the cutting element 14 from the tool carrier 12 ofthe holder 10 it may be replaced by a new cutting element 14.

In an embodiment of the tool as claimed in the invention which is notdetailed, provision may be made such that one of the two locking pieces32 is designed to be radially shorter than the other, with the slottedreceiving channel 30 having one accordingly longer and one shorterreceiving flank 58. In this way it is then possible to implement thefastening and loosening process in only one position; this may be ofimportance when the machining fixture is provided for example with onlyone machining edge (not shown).

1. A machining tool for chip removal, a milling tool in particular,having a holder (10) wherein there is provided a tool carrier (12) for acutting element (14) which has a machining part (16) and a fasteningpart (18), characterized in that the fastening part (18) has a base part(20) which may be inserted into the tool carrier (12) in a receivingposition (22) and which when turned into the locking position (26)extends under at least one holding projection (26) in the tool carrier(12) in order thereby to be usable for metal cutting with the cuttingelement (14).
 2. The tool as claimed in claim 1, wherein the toolcarrier (12) on the end side has a receiving channel (30) which extendstransversely to the longitudinal axis (28) of the holder (10) and whichmay be penetrated by at least one locking piece (32) of the base part(20), and wherein the receiving channel (30) on the edge side isbordered by the respective holding projection (26) under which therespective locking piece (32) may extend in the locking position (24).3. The tool as claimed in claim 2, wherein the receiving channel (30) onthe end side leads into a receiving cone (34) which widens toward theexterior and which may be brought into contact with a correspondinglyconfigured centering cone (36) of the fastening part (18) in the lockingposition (24) of the cutting element (14).
 4. The tool as claimed inclaim 3, wherein the centering cone (36) is adjoined by the machiningpart (16) with at least one machining edge (38), preferably atriple-edged cutting plate (40), and wherein between the centering cone(36) and the machining edge (38) there is a connecting part (42) whichis pulled in the longitudinal axis (28) of the holder (10) in thelocking position (24) of the cutting element (14) against the outercircumferential edge (46) of the receiving cone (34).
 5. The tool asclaimed in claim 2, wherein on the base part (20) there are two lockingpieces (32) which are diametrically opposite one another and wherein,located on the free end of the fastening part (18), the locking piecesare connected to the centering cone (36) which widens toward exterior byway of a fastening shaft (48).
 6. The tool as claimed in claim 2,wherein the respective locking piece (32) on its side adjacent to thecentering cone (36) is provided with a bevel (50) which slopes down inthe direction of the free end of the fastening part (18).
 7. The tool asclaimed in claim 2, wherein in the interior (52) of the tool carrier(12) assigned to each locking piece (32) there is at least one part of athread (54) with a lead beginning on the holding projection (26), whichlead is oriented in the direction of the inside wall (56) of the toolcarrier (12), which wall is at least partially closed on the end side.8. The tool as claimed in claim 5, wherein one of the two locking pieces(32) is designed to be radially shorter than the other and wherein theslotted receiving channel (30) has one correspondingly longer and oneshorter receiving flank (58).
 9. The tool as claimed in claim 1, whereinthe cutting element (14) after insertion into the tool carrier (12) maybe moved against the direction of machining of the respective machiningedge (38) into its locking position (24) and in the opposite directionof rotation into a receiving position (22).
 10. The tool as claimed inclaim 5, wherein the axial length of the fastening shaft (48) is atleast greater than the length of the diametrically opposite holdingprojections (26), especially relative to their bevels (50), which lengthis measured in the longitudinal axis (28) of the holder (10).